A mono-lower-alkylmonoalkanolamine is a useful compound which has a high commercial demand as an intermediate material for general organic synthesis, for example, a cationic flocculating agent, a drug or agricultural chemical intermediate, an etching liquid for resin, a softener for synthetic fibers, a corrosion inhibitor, a neutralizing agent for petroleum refining or petroleum process, or a dispersant.
The production of a mono-lower-alkylmonoalkanolamine by a reaction of a mono-lower-alkylamine and an alkylene oxide has so far been reported in literatures and others (for example, Nonpatent Literature 1).
In the reaction of a mono-lower-alkylamine and an alkylene oxide, both a mono-lower-alkylmonoalkanolamine and a mono-lower-alkyldialkanolamine are formed concurrently. In this reaction, for selectively obtaining a mono-lower-alkylmonoalkanolamine, the mono-lower-alkylamine must be used in large excess with respect to the amount of the alkylene oxide. For this reason, a great amount of unreacted mono-lower-alkylamine remains in the reaction.
As a method for producing a mono-lower-alkylmonoalkanolamine by a reaction of a mono-lower-alkylamine and an alkylene oxide, a zeolite catalyst method using zeolite as a catalyst has been proposed (Patent Document 1).
An example of a conventional apparatus for producing a mono-lower-alkylmonoalkanolamine using a zeolite catalyst is illustrated in FIG. 17. In FIG. 17, reference numeral 1 denotes a reactor, which is filled with a zeolite catalyst, and raw material I (mono-lower-alkylamine) and raw material II (alkylene oxide) are fed to the reactor 1 where they are reacted with each other by a zeolite catalyst method to produce a product 2 including unreacted raw materials. The product 2 including unreacted raw materials includes an unreacted mono-lower-alkylamine (unreacted raw material I) and an unreacted alkylene oxide (unreacted raw material II) as unreacted raw materials, and these unreacted raw materials and a reactive product 3 are separated by distillation by means of an unreacted-raw-material-recovery distillation column 4, and the unreacted mono-lower-alkylamine (raw material I) and alkylene oxide (raw material II) which are separated and recovered are fed back to the reactor 1 as an unreacted raw material 5.
Water and light component 7 are removed by a distillation method by means of a non-aqueous distillation column 6 from the reactive product 3 derived from the unreacted-raw-material-recovery distillation column 4, and a reactive product 3a from which the water and light component have been removed is fed to a purification and distillation column 8. The term “non-aqueous” means a state of the contents having a moisture content of 1000 ppm or less.
The reactive product 3a from which the water and light component have been removed is fed to the purification and distillation column 8 where a mono-lower-alkylmonoalkanolamine and a mono-lower-alkyldialkanolamine (dimer as a residue) formed by a reaction are separated by a distillation method, and the mono-lower-alkylmonoalkanolamine is recovered as a desired purified reactive product 9.
On the other hand, as a method for producing a mono-lower-alkylmonoalkanolamine using no zeolite catalyst, a method in which the production is conducted under, for example, supercritical conditions (conditions such that the temperature is 100 to 200° C. and the pressure is 17 to 24 megapascals [MPa]) has been proposed (Patent Document 2).
As a method for producing a mono-lower-alkylmonoalkanolamine by a reaction of a mono-lower-alkylamine and an alkylene oxide, a method in which the reaction is conducted in the presence of water (hereinafter, “water catalyst method”) has been well known. However, this method has a problem in that the removal of a great amount of water by distillation in the purification system requires a large heat load.
Further, a method for producing monomethylaminoethanol from monomethylamine and ethylene oxide is disclosed (Patent Document 3). In the method described in Patent Document 3, crude liquid and alcohol are mixed and then fed to a distillation column for amine recovery system, or crude liquid and alcohol are individually fed through separate lines to the distillation column to recover unreacted monomethylamine.
Nonpatent Literature 1: “Surface Active Agent” by Ryohei ODA and Kazuhiro TERAMURA, p. 262-263, Maki Shoten, 1965
Patent Document 1: Japanese Patent Application Laid-open No. 2004-275933
Patent Document 2: Japanese Patent Application Laid-open No. S59-13751
Patent Document 3: Japanese Patent Application Laid-open No. H8-333310